Flue-gas purification and reclamation system and method thereof

ABSTRACT

A flue-gas purification system includes a flue-gas cycling system, a reactor, an absorbent adding system having at least a catalytic absorbent, wherein the catalytic absorbent is being gasified for reacting with the flue-gas in the reactor in a homogenous gas-gas phase reacting manner. Therefore, the purification system has fast reaction rate between the pollutants of the flue-gas and the catalytic absorbent, which is preferably ammonia, to efficiently remove pollutants, so as to effectively purify the flue-gas.

CROSS REFERENCE OF RELATED APPLICATION

This application is a Continuation application of a non-provisionalapplication, application Ser. No. 12/803,535, filed Jun. 28, 2010, nowU.S. Pat. No. 8,110,164.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to a system and method of the wastetreatment, and more particularly to a flue-gas purification andreclamation system and method, which has high efficient removal rate ofpollutants or contaminations in the wastes of flue-gas and to remove twoor more contaminations within the flue-gas at the same time.

2. Description of Related Arts

The fossil fuel power plants are mainly provided for generating andsupplying the power or energy for most of the manufactures. For example,the manufacture may burn the coal or oil to produce steam for the steamturbines that drives the electricity generator of the manufacture. Theexhaust flue-gas from fossil fuel power plants is well known as one ofthe main pollution culprits or sources. The flue-gas usually contains aplurality of pollutants or contaminations, such as sulfur dioxide SO₂ orother sulfur oxides; nitrogen oxides NO_(x)—NO and NO₂; and carbondioxide CO₂ or other carbon oxides.

Those contaminations directly discharge to the atmosphere without beingtreated to reduce the contaminated contains has damaged the environmentof the earth. For instances, the SO₂ and NO₂ has caused the acidrainfall, which can damage buildings, historical monuments, and hasdirectly linked to the human health; the nitrogen oxides NO_(x) is alsothe main reason that cause the Photochemical smog; and the carbondioxide CO₂ has caused the greenhouse effect, which cause the globalwarming.

In order to better protect the environment, there are variety oftreatments and processes for reducing and minimizing the contaminationamount of the industrial wastes mainly from the flue-gas. Traditionally,most of the existing methods for removing the contaminations of theflue-gas are focusing on separately removing the SO₂ and NO_(x). Thereare mainly two types of flue-gas purification for the treatment ofremoving the sulfur oxides: dry method and wet method of gaspurification technologies.

Take the dry desulfurization for instance. The dry desulfurizationusually employs solid absorbent or catalyst for removing the sulfurdioxide SO₂ of the waste, such as activated carbon adsorption, molecularsieve adsorption, oxidation, and metal oxidation adsorption etc. Theadvantage of the dry desulfurization is that no discharging of wastewater, and/or waste acid, so that the dry desulfurization is able tominimize and reduce the secondary pollution thereof. However, the mainconcerns are the desulfurization efficiency is low, the equipments ofdry desulfurization are bulky and occupy dramatic large space thereof,and the cost of the equipment and it process is high.

Take the wet desulfurization as another example of gas purification. Thewet desulfurization for removing the sulfur oxides SO₂ includes thelimestone-gypsum method, sodium alkali absorption method, ammoniaabsorption, aluminum method, catalytic oxidation, and catalyticreduction methods. The wet method of the limestone-gypsum method iscommonly used worldwide and is the most mature technology for removingthe sulfur oxides nowadays.

The limestone-gypsum method is highly efficient of desulfurization andis stable during the process of desulfurizing. The absorbent used in thelimestone-gypsum has highly absorbing rate, which is suitable for largeamount of waste with high concentration of the sulfur oxides gas, andhas high adaptability of the coal. The absorbent of the limestone-gypsumwet method is low in cost. The side products generated from thelimestone-gypsum process are able to be utilized for other commercialpurposes.

Although the limestone-gypsum method is currently one of the mostpopular methods having the above mentioned advantages, thelimestone-gypsum wet method still occupies too much space and high inmanufacturing cost. The process also requires a large amount of water,and generate great amount of waste water and other waste gases, such aswaste carbon dioxide and other greenhouse gases, so that it brings theissue of serious secondary pollution. The side products of the wetdesulfurization treatment are usually wet, so that it is relatively moredifficult for treating the side products therefrom. The waste water fromthe wet process of the limestone-gypsum has to be treated beforedischarging. Therefore, the cost of the treatment of the wastes is againincreased.

There are relatively more flue-gas treatment technologies for removingthe nitrogen oxides, such as selective catalytic reduction (SCR), liquidabsorption, microbial absorption, non-selective catalytic reduction,carbon reduction method, catalytic decomposition method, liquid membranemethod, SNRB denitrification technology, and feedback oxidationadsorption denitrification technology etc. However, there is only theselective catalytic reduction (SCR) method has been widely applied forthe waste treatments.

The selective catalytic reduction method is using the NH₃ as thereducing agent to selectively react the NO_(x) of the waste via catalystto form non-toxic and pollution free N₂ and H₂O. Under the temperaturerange of 200 to 400° C. and the stoichiometric ration of 1:1 of NH₃ toNO_(x), the removal rate of the NO_(x) is as high as 80 to 90%. However,the catalyst used in this process is high poisoning; and the poroussurface of the catalyst tends to be easily clogged up, which is criticalto catalyzing reaction, to gradually decrease the removal rate thereof,so that the process is unstable, consumes a large amount of catalyst,and high in operative cost. Furthermore, the selective catalyticreduction method is not suitable for high capacity and highconcentration of the NO_(x) of the waste.

Although the mainstream of the industrial process of flue-gaspurification is using wet method for removing the sulfur oxides, andusing dry method for removing the NO_(x), there are some other methodsfor removing both sulfur oxides and nitrogen oxides. For examples,plasma, electron beam method, CuO method, SNAP method etc. Those methodsfor moving both SO_(x)/NO_(x) at the same time are looking for atreatment that is more efficient and more economic than the methods ofseparately treating the SO_(x) and NO_(x). Some of the method forremoving both SO_(x)/NO_(x) may be able to achieve the desired removalrate. For instance, the industrial art of removing both SO_(x)/NO_(x)could be performed by the lime/limestone flue-gas desulfurization FGDsystem, which is used for removing the SO2 while using the catalyticmethod SCR for removing the NOx. The above mentioned method for removingboth SOx/NOx is able to remove 90% of sulfur dioxide and 30 to 80% ofnitrogen oxides and combines the wet and dry method, so that the FGDsystem of the wet method and the SCR system of the dry method are ableto independently remove its respective targeted contaminations toachieve each contaminations desired removal rate.

However, the method for removing both SO_(x)/NO_(x) via combining thewet and dry methods also inherited the disadvantages of both wet and drymethods as mentioned above. Therefore, the method for removing bothSO_(x)/NO_(x) tends to be costly in both equipment and operation,require a large amount of water, and have secondary pollution. Theactivity of the catalyst is gradually decreasing, so that the removingrate keeps decreasing. Most important of all, none of the existingmethods consider to remove the carbon dioxide separately or remove theSO_(x)/NO_(x) and the carbon dioxide at the same time.

SUMMARY OF THE PRESENT INVENTION

The invention is advantageous in that it provides flue-gas purificationand reclamation system and its method thereof, wherein the purificationsystem is able to high efficiently remove the contaminations in theflue-gas.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, which has the removal rate ofremoving the SO₂, and NO₂ as high as 98% or more; and a removal rate ofCO₂ as high as 30% or more.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, which is able to remove two or morecontaminations in the flue-gas, wherein the system is able tosignificantly remove both SO_(x), NO_(x), and CO₂ at the same time.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, wherein the gas ammonia is reactingwith the SO₂, NO₂, and CO₂ within the flue-gas to form the gas-gas phasecatalytic acid-base reaction via gas film control. The gas-gas phasereaction between the contaminations and the gas phase ammonia has areaction rate that is fast enough to be applied to the industrialprocess for the waste treatment. The ammonia used in the process of thesystem has high utilization rate. Compare to the gas-solid phase orgas-liquid phase reaction of the limestone method, the gas-gas phasereaction of the ammonia and the contaminations has a relatively higherreacting rate and contamination removal rate.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, which is able to easily incorporatewith most of the new or old type chemical engineering processmanufactures.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, which is small in size, and low costof the equipments of the system, so as to minimize the requirement ofthe occupied space of the system.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, wherein the system is simple foroperation and low in operation cost.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, wherein the ammonia for reacting withthe targeted contaminations is inexpensive and has high utilizationrate, so as to cost down the process for the waste treatment.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, wherein the amination purificationapplied the ammonia to mainly react with SOx, NOx, and CO₂ is suitablefor most petroleum fuel, coal, and natural gas related processes.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, wherein the gasified ammonia is ableto firstly involve into the purifying reaction mechanism as a catalystfor reducing the activation energy thereof, and then secondaryparticipating into the purifying reaction process for reacting with thecontaminations respectively. Therefore, the process of purificationsystem and method is further simplified and the cost of raw material forreacting with the contaminations is further minimized.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, wherein no water is required to beused during the process, so that the flue-gas purification system isable to eliminate the process of waste water treatment, so as toconserve water.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, wherein there is no secondarypollution, so as to cost down the treatment of the purification systemof present invention.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, wherein the system minimizes theclogging phenomena, so as to enhance the stability of the purificationsystem.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, wherein the products from thereactions of the purification process are solid ammonium salt compounds,wherein after the process of removing the dust to collect the solidammonium salt compounds, the products are able to be reused orre-processed for variety purposes, such as artificial compoundfertilizer, so as to achieve the reclamation of the waste.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, wherein the purification process hasthe multi-functions of desulfurization, denitrification, reduction ofcarbon, and removal of dust, such as the product of the solid ammoniumsalt compounds.

Another advantage of the invention is to provide flue-gas purificationand reclamation system and method, which is able to apply to varietyapplications. For examples, the purification system is able to apply tothe treatment of acid harmful gases, such as hydrogen fluoride andhydrogen chloride; and the purification system is able to be used forthe treatment of waste gas from the car.

Additional advantages and features of the invention will become apparentfrom the description which follows, and may be realized by means of theinstrumentalities and combinations particular point out in the appendedclaims.

According to the present invention, the foregoing and other objects andadvantages are attained by providing a flue-gas purification system,which comprises:

a reactor;

a flue-gas cycling system, which has a channel having a deliveringopening for conveying exhaust flue-gas from said channel to saidreactor;

an absorbent adding system containing at least a catalytic absorbent,wherein

said catalytic absorbent is being gasified to a gas phase and beingdelivered into said reactor, in such a manner that a plurality ofpollutants of the flue-gas are able to react with said catalyticadsorbent under a homogenous gas-gas phase condition to form products ofnon-toxic compounds, so as to efficiently purify the flue-gas.

In accordance with another aspect of the invention, the presentinvention also provides a method for purifying the flue-gas, whichcomprises the following steps.

(A) Convey the flue-gas from the delivering opening of the channel ofthe flue-gas cycling system into the reactor.

(B) Gasify the catalytic absorbent of the absorbent adding system to thegas phase thereof and convey the gasified catalytic absorbent into thereactor. Therefore, the catalytic absorbent, preferably the gas phaseammonia, is able to react with the pollutants in the flue-gas forremoving the pollutants, so as to purify the flue-gas when the flue-gasexits the reactor.

(C) Discharge the purified flue-gas into the air ambient.

Still further objects and advantages will become apparent from aconsideration of the ensuing description and drawings.

These and other objectives, features, and advantages of the presentinvention will become apparent from the following detailed description,the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a flue-gas purification system according toa preferred embodiment of the present invention.

FIG. 2 is a table of the comparisons of removal rate and efficiency ofpollutants between the traditional technologies and the presentpurification system.

FIG. 3 is a flow chart of a flue-gas purification method according tothe preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 of the drawing, a flue-gas purification systemaccording to a preferred embodiment of the present invention isillustrated, wherein the flue-gas purification system comprises at leasta reactor 10, a flue-gas cycling system 20, and an absorbent addingsystem 30.

The flue-gas cycling system 20 has at least a channel having adelivering opening for conveying exhaust flue-gas from the flue-gascycling system 20 into the reactor 10.

The absorbent adding system 30 operatively communicating with thereactor 10, wherein the absorbent adding system 30 contains at least acatalytic absorbent and arranged for delivering the catalytic absorbentfrom the absorbent adding system 30 into the reactor 10. Before thecatalytic absorbent being delivered into the reactor 10, the catalyticabsorbent is preferably being gasified to the gas phase, so that theabsorbent is able to react with the flue-gas in a homogenous gas-gasphase manner, so as to dramatically increase the reaction rate thereof.

The catalytic absorbent is preferably ammonia, wherein the ammonia beinggasified to the gas phase is able to react with the contaminationswithin the flue-gas in a reaction rate, which is able to apply to thechemical process for industrial applications. The gas phase ammonia isable to quickly react with the pollutants of the flue-gas to formvariety of non-toxic compounds. For examples, the gasified ammonia isable to react with the sulfur dioxide SO₂ to form ammonium sulfate((NH₄)₂SO₄); the gasified ammonia is able to react with the nitrogenoxides NOx to form ammonium nitrate (NH₄NO₃); and the gasified ammoniais able to react with the carbon dioxide CO₂ to form ammonium carbonate((NH₄)₂CO₃). Other compounds may be also formed by the series reactionsof the catalytic absorbent and flue-gas, such as the fly ash. Moredetails of each of the reactions within the reactor 10 will be describedlater.

As will be readily appreciated that using the ammonia as the catalyticabsorbent not only can remove the harmful pollutants, such as SOx, NOx,and CO₂, but also form the non-toxic final products from the reactantsof ammonia and the pollutants in the flue-gas. The final products, suchas the above mentioned ammonium salts, can be used as fertilizers, sothat the flue-gas purification system is able to purify and recycle thepollutants of the flue-gas, so as to achieve the reclamation purpose.

It should be noted that the reactions of the gas phase flue-gas and thegas phase of the catalytic absorbent are fast chemical reactions thatare able to efficiently consume the pollutants within the flue-gas viathe absorption processes of catalytic oxidation reactions, photolysis,complex chin reactions, and/or the dust removal process. There are noextra other natural sources are needed or involved in the purificationsystem of the present invention. There is no wastewater or othersecondary pollutions of the side products of the reactions aregenerated. Thereby, the purification system is able to high efficientlyremove the pollutants within the flue-gas.

In the preferred embodiment of the present invention, the reactor 10 ispreferably a Venturi homogenous gas-gas phase reactor 10, which has theVenturi type design for the gas phase ammonia being able to fully mixand contact with the gas phase flue-gas to maximize the efficiency ofthe reactions therebetween.

Accordingly, a heat exchanger unit 40 is further provided forefficiently supplying the predetermined heat energy to gasify liquidphase ammonia into gas phase thereof before the ammonia entering thereactor 10.

The heat exchanger unit 40 is preferably arranged that the flue-gas isentering the heat exchanger unit 40 for being conveyed into the reactor10, wherein the flue-gas, which is normally has a temperature around 120to 160° C. at the delivering opening of the channel of the flue-gascycling system 10, is arranged to flow within the heat exchanger unit 40as a heat transfer medium, in such a manner that the heat exchanger unit40 is able to efficiently employ the heat energy from the flue-gasitself to gasify the ammonia substantially without significant extraenergy or power for gasifying the ammonia, so as to cool down theflue-gas to a desired temperature.

In other words, the heat exchanger unit 40 basically has at least twosets of pipes, wherein the first set of pipes allow the flue-gas toenter an input end of the first set of pipes and exit an output end ofthe first set of pipes to enter into the reactor 10, while the secondset of pipes convey the liquid phase of the ammonia entering an inputend of the second set of pipes and exit an output end of the second setof pipes with the gas phase ammonia. Thereby, the flue-gas with highertemperature within the first set of the pipes is arranged as a heatexchange medium for heating the liquid phase of the ammonia within thesecond set of pips to heat exchange therewith, so as to gasify theammonia from liquid phase to the gas phase. Therefore, the flue-gas isable to quickly react with the gas phase ammonia of the catalyticabsorbent for being purified.

It is worth to mention that through the heat exchanger unit 40, theammonia is able to absorb the heat from the higher temperature of theflue-gas, so as to efficiently utilize the internal energy of thepurification system to gasify the liquid phase ammonia. The heatexchanger unit 40 is also able to convey the gasified ammonia and thecooled flue-gas into the reactor 10 for reacting with each other in thegas-gas phase reacting manner.

As will be readily appreciated that the catalytic absorbent, which isembodied as gasified ammonia, is preferably being delivered into thereactor 10 in a three stages manner. In other words, each of the stageshas a specific reactive conditions, such as a predetermined temperature,concentration, and/or pressure, for mainly purifying a targetedcontamination of the flue-gas, so that the variety reactive conditionsof each of the reacting stages are able to further enhance the reactionrate, so as to purify multiple contaminations substantially at the sametime via the single purification system of the present invention.

For instance, the sulfur dioxide is being delivered into the first stagefor essentially fully reacting with the ammonia, wherein the sulfurdioxide may further being conveyed into the second stages in the reactor10 for further reacting with the ammonia while the second stage isdesigned with the predetermined reactive conditions for mainly reactingwith nitrogen dioxide, in such a manner that the purification system ofthe present invention is able to efficiently and simultaneously purifytwo or more contaminations. Therefore, the gas-gas phase reactionsbetween contaminations of the flue-gas and the ammonia in the reactor 10is preferably arranged to form the two levels and three stages fullycontacting arrangement to have more efficient purification system.

Accordingly, a dust remover unit 50 is preferably provided forcollecting and removing the dust from the flue-gas or the productsgenerated from the reactions within the reactor 10. The dust, which mayinclude the fly ash within the flue-gas and the ammonium salts, which isformed via the reactions of the gas-gas phase reactants of the flue-gasand the catalytic absorbent. Therefore, the pollutants of the flue-gasare reacted with the gas phase ammonia in the reactor 10 for removingthe pollutants and purifying the flue-gas. After the reactions aresubstantially finished, the dust remover unit 50 is able to remove thefly ash and the ammonium salts of the dust from the flue-gas before theflue-gas being discharged into the air ambient.

The dust remover unit 50 may further comprise a dust removing device 51for removing the dust and a solid product collector 52 mainly for thecompounds of ammonium salts generated from the reactions between thepollutants and the catalytic absorbent. Therefore, the flue-gas beingpurified by the reactor 10 and filtered by the dust removing device 51of the dust remover unit 50 is able to discharge into the atmospherewith relatively cleaner gas. The ammonium salts are able to be furtherseparated and collected via the solid product collector 52 forreclamation, such as reuse the collected ammonium salts for using as thefertilizer.

After separating the dust and the purified flue-gas, the purifiedflue-gas is further conveyed to pass through a fog separator 53 forseparating the gas ammonia and the purified flue-gas. The gas ammonia isthen being redirected to enter into the flue-gas cycling system forrecycling the ammonia, and the purified flue-gas is being delivered intothe heat exchanger unit 40 for being further cooled down to apredetermined temperature before being discharged into the air ambient.The purified flue-gas is further being cooled via the heat exchangerunit 40 and then being exhausted into the atmosphere therefrom.

Accordingly, the dust within the reactor 10, which is from the ash andthe solid ammonium salt compounds of the products of the reactions, ispreferably entering a Venturi tube of the Venturi type reactor 10 forbeing gradually concentrated, and then through the collisions andaggregation processes, the sizes of the particles of the dust areincreased to the predetermined sizes, so that the dust removing device51 is able to remove and separate the dust from the flue-gas. The dustremoving device 51 may be an electrostatic precipitator or a bag typedust remover for collecting and/or removing the dust from the flue-gas.

The purification system may further comprises a monitoring system 60,wherein the monitoring system 60 is able to monitor variety oftemperatures, concentrations, pressures, and other parameters at varietyof check points of the purification system, so as to control thepurification system. Therefore, the flue-gas of the flue-gas cyclingsystem 10 normally has a temperature around 120 to 160° C. beforeentering into the heat exchanger unit 40, a temperature around 60 to 80°C. after exiting the heat exchanger unit 40 and before entering thereactor 10, and a temperature around 25 to 50° C. after final exitingthe heat exchanger 10 after reacted with the catalytic absorbent in thereactor 10. In other words, the purified flue-gas is about 25 to 50° C.when exiting the purification system and being discharged into the air.

The monitoring system 60 may be further electrically linked to thecatalytic absorbent adding system 30, wherein the absorbent addingsystem 30 is able to automatically add a predetermined amount of thecatalytic absorbent into the heat exchanger 40 in responsive to theconcentrations of each of pollutants or contaminations of the flue gasbefore entering and/or after entering the reactor 10, the temperatures,pressures, and other parameters measured via the monitoring system 60,so as to form a automatic self-absorbent-flow-rate control system.Therefore, the monitoring system 60 is able to collect the parameters atany measuring points of the purification system, such as temperature andpressure of flue-gas before entering the reactor 10; or concentration ofgas ammonia in the first stage within the reactor 10.

Accordingly, the gasified ammonia of the catalytic absorbent is able toreact with the steam or water vapor (H₂0_((g))) within the flue-gas toform the ammonium water complex (NH₃.H₂O), so that the SOx, NOx, andCOx, such as SO₂, NO₂, and CO₂, are able to quickly react with theammonium water complex to occur gas-phase homogeneous nucleationreactions, so as to achieve the removal of the SO₂, NO₂, and CO₂ ofpollutants of the flue-gas.

It will be readily appreciated that normally the flue-gas contains 50%of N₂, 8% of O₂, 30% of CO₂, 9% of H₂O, and other gases of pollutants inthe flue-gas, such as sulfur dioxides, nitrogen oxides, and fly ash.Theoretically, the H₂0_((g)) is able to react with the SO₂, NO₂, andCO₂, the reactions between SO₂, NO₂, and CO₂ and the steam water isextremely slow that it is impossible to directly utilize to theindustrial applications. Under the added catalytic absorbent, embodiedas gas phase ammonia, the water molecular H₂O and ammonia molecular NH₃are able to form the ammonium water complex (NH₃.H₂O) through thehydrogen-bond therebetween, so as to quickly further react with thecontaminations of flue-gas to remove the SOx, NOx, and CO₂.

Accordingly, the reactions of each of the pollutants and the catalyticabsorbent are described as followings.

The nitrogen oxides of the pollutant of the flue-gas are being removedvia a series of denitrification processes. The NO in the flue-gas isfirst being oxidized to form the NO₂. The NO₂ is reacting with the watermolecular within the NH₃.H₂O via the reduction-oxidation reaction toform the nucleation reaction to form the solid phase ammonium nitrateand gas phase nitrite, wherein partial of the nitrite further reactswith the ammonia to form the nitrate. The reaction of the nitrogenoxides and the water molecular of the ammonium water complex via theammonia catalyst is shown below:2NO+O₂→2NO₂2NO₂+NH₃—H₂O→NH₄NO₃+HNO₂HNO₂+NH₃→NH₄NO₂

The sulfur oxides removal is through a series of multi-chemicalprocesses, which involves acid-base reactions, oxidation reactions,radical reactions, and chain reactions.

The acid-base reactions of the sulfur dioxides is through nucleationreaction of the sulfur dioxides reacting with NH₃—H₂O, which isendothermic reaction, to form the solid NH₄HSO₃ and ammonium sulfite(NH₄)₂SO₃. The reaction equations are shown in the following:NH₃—H₂Og _((Gas))+SO₂ g _((Gas))→NH₄HSO_(3s),2NH₃—H₂Og _((Gas))+SO₂ g _((Gas))→(NH₄)₂SO₃

The oxidation reaction: the NH₄HSO₃ and the (NH₄)₂SO₃ are oxidized viathe oxygen, carbon dioxides, and ammonium nitrate to form the NH₄HSO₃and ammonium sulfite (NH₄)₂SO₃. The reaction equations are shown in thefollowing:NH₄HSO_(3s)+O_(2g)→NH₄HSO_(4s)NH₄HSO_(4s)+NH₃→(NH₄)₂SO₄NH₄HSO_(3s)+NO_(2g)→NH₄HSO_(4s)+NONH₄NO₃+NH₄HSO₃→(NH₄)₂SO₄+HNO_(2g)

The chain reaction equations of the sulfur oxides are also shown in thefollowing:HONOg+hν---→OH+NOOH+SO₂--→H₂SO₄NH₃+H₂SO₄--→NH₄HSO₄NH₃+NH₄HSO₄--→(NH₄)₂SO₄

Therefore, through the processes of acid-base reactions, oxidationreactions, radical reactions, and chain reactions, the sulfur oxides ofthe pollutants in the flue-gas are able to be removed after the seriesdesulfurization reactions within the reactor 10.

The decarbonization process is further involved in the series reactionsof contaminations removal in the reactor 10, wherein the carbon dioxide,which may be hard to react with gas or liquid phase water molecular, areable to collide with the NH₃—H₂O to start the homogeneous nucleationreactions to form the solid phase compounds of NH₄HCO₃ and the ammoniumcarbonate (NH₄)₂CO₃, so as to remove the carbon oxides and to form theproducts of ammonium salts, which is able to be recycled for beingreused as fertilizer. The reaction equations are shown in the following:CO₂+NH₃—H₂O→NH₄HCO₃NH₄HCO₃+NH₃→(NH₄)₂CO₃

Referring to FIG. 3 of the drawings, a method of purifying flue-gasaccording to the preferred embodiment of the present invention isillustrated, wherein the method comprises the following steps.

(A) Convey the flue-gas from the delivering opening of the channel ofthe flue-gas cycling system 20 into the reactor 10.

(B) Gasify the catalytic absorbent of the absorbent adding system 30 tothe gas phase thereof and convey the gasified catalytic absorbent intothe reactor 10. Therefore, the catalytic absorbent, preferably the gasphase ammonia, is able to react with the pollutants in the flue-gas forremoving the pollutants, so as to purify the flue-gas when the flue-gasexits the reactor.

(C) Discharge the purified flue-gas into the air ambient.

Before the step (C), the method may further comprises a step of removingdust in the reactor via the dust remover unit 50, so that the dust,including the fly ash and the yield solid phase products from the seriesreactions within the reactor 10, is able to be removed to further purifythe flue-gas, so as to prevent the dust clogging the system. The dustmay be separated from the purified flue-gas via the dust removing device51 as mentioned above.

After the step of removing the dust, a step of collecting the solidammonium salt compounds and other solid particles via the solid productcollector 52 may further provided, so that the solid products generatedin the reactor 10 is able to be further utilized as another usage, suchas ammonium fertilizer.

According to the preferred embodiment of the present invention, beforethe step (A), a step of providing the heat exchanger unit 40 may furtherprovided. Therefore, the step (A) may further comprises a step ofdelivering the flue-gas into the first set of pipes of the heatexchanger unit 40 as the heat exchanging medium thereof; and conveyingthe flue-gas to exit the heat exchanger unit 40 and enter into thereactor 10.

The step (B) may further comprises a step of delivering the liquidammonia of the catalytic absorbent into the second set of pipes of theheat exchanger unit 40, so that the liquid ammonia is able to absorb thepredetermine amount of heat energy from the heat exchanging medium ofthe flue-gas in the first set of pipes for being gasified. The step (B)further comprises a step of conveying the catalytic absorbent to exitthe heat exchanger unit 40 and to enter into the reactor 10.

It is worth to mention that the ammonia of the catalytic absorbent ispreferably to be delivered into the reactor in the above mentioned threestages manner, so as to maximize the reaction rate between the absorbentand each of the pollutants of the flue-gas. Therefore, the purificationsystem is able to obtain a relatively higher removal rate of thecontaminations of the flue-gas.

Accordingly, the method may further comprises a step of delivering saidcatalytic absorbent into said reactor in a multiple stages manner, suchas above mentioned three stages manner, and preferably at least two ormore stages, so that each stages is able to target specific pollutantsof the flue-gas to maximize the purification rate of each of thepollutants. Therefore, the method is able to achieve purifying multiplepollutants in the flue-gas at the same time via the same reactor 10 andthe purification system. There is no need for building and purchasinganother equipment or system for removing variety of pollutants offlue-gas. Thereby, the equipment cost of the facility or manufacture isminimized, and meanwhile, the required area for building thepurification system is minimized.

Before the step of discharging the purified flue-gas and after the stepof removing dust, a step of separating the gas ammonia and the purifiedflue-gas may further provided, wherein the ammonia is able to beredirected into the flue-gas cycling system 10 for being reused and thepurified flue-gas is able to be directed to the heat exchanger 40 forbeing further cooled to the predetermined temperature to be dischargedinto the air therefrom.

In the preferred embodiment of the present invention, a step ofproviding the monitoring system 60 may further provided, wherein themonitoring system 60 is able to detect the temperatures, pressures,concentrations of each of the pollutants of the flue-gas at variety ofcheck points of the purification system, so as to further monitor thesystem for enhancing efficiency and safety thereof. The monitoringsystem 60 is able to electrically link with the absorbent adding system30 for controllably, automatically, and continuously adding thepredetermined amount of the catalytic absorbent into heat exchanger unit40 as described above.

Therefore, the purification system of the present invention has at leastthe following advantages.

1. There is substantially no significant external energy is required.The heat exchanger is able to utilize the internal heat energy of theflue-gas of the purification system to gasify the ammonia, so as to savethe energy.

2. The gas-gas phase homogenous reactions between the gasified ammoniaand the flue-gas has fast reaction rate and high yield rate of theproducts of ammonium salt compounds of the reactions, so that thepurification system is able to high efficiently remove the pollutants inthe flue-gas. The SO₂, NO₂ of the pollutants removal rate are higherthan 98%, and the CO₂ is higher than 30%. The removal rate, compare tothe existing methods as shown in FIG. 2, is significantly improved andenhanced.

3. The main consumed chemical compound is the ammonia of the absorbent,which is cheap and has highly reusable rate, so as to minimize the costof the purification operation.

4. The entirely equipments, such as the reactor 10, the absorbent addingsystem 30, the heat exchanger unit 40, and the dust remover unit 50,occupied relatively smaller spaces, and are simple in structure, so thatthe installation and the equipments costs are minimized.

Furthermore, the signal purification system has multi-functions ofdesulfurization, denitrification, reduction of carbon, and removal ofdust, so that the purification system not only enhance the efficiency ofpurifying the pollutants of the flue-gas, but also minimize the spacesrequired for building the purification system of present invention.

5. The purification system has high flexibility for incorporating withvariety of applications or facilities, so that the purification systemis able to be widely applied in variety industrial fields. For examples,the purification system is able to apply to the treatment of acidharmful gases, such as hydrogen fluoride and hydrogen chloride; and thepurification system is able to be used for the treatment of waste gasfrom the car.

6. No water is required for purifying the flue-gas, so that thepurification system is able to conserve the natural source of water. Nowaste water or any other types of secondary wastes are formed via thepurifying process of the purification system, so that the flue-gaspurification system is able to eliminate the process of secondary wastetreatment.

7. No strong corrosive chemical compounds added into or generated fromthe reactions, so that the equipments of the purification system hasrelatively longer usage life. The dust remover unit is able to collectand remove the dust, such as fly ash and any other solid particles, sothat the clogging issue is minimized, so as to enhance the stabilityduring the operation of the purification system and to cost down themaintenance fee thereof.

8. The ammonium salt compounds generated from the reactions of thepurifying process are able to be further reused, so that the flue-gasnot only can be purified but also be reclaimed.

One skilled in the art will understand that the embodiment of thepresent invention as shown in the drawings and described above isexemplary only and not intended to be limiting.

It will thus be seen that the objects of the present invention have beenfully and effectively accomplished. It embodiments have been shown anddescribed for the purposes of illustrating the functional and structuralprinciples of the present invention and is subject to change withoutdeparture from such principles. Therefore, this invention includes allmodifications encompassed within the spirit and scope of the followingclaims.

1. A flue-gas purification system, comprising: a reactor; a flue-gascycling system for conveying at least one exhaust flue-gas to saidreactor; and an absorbent adding system containing at least a catalyticabsorbent, wherein said catalytic absorbent is being gasified to a gasphase and being delivered into said reactor so that a plurality ofpollutants of said flue-gas are able to react with said catalyticadsorbent to form a series of reactions therebetween under a homogenousgas-gas phase condition and a reacting temperature at 160° C. or less,so as to form final products in solid state after said series reactionsto efficiently purify said flue-gas.
 2. The flue-gas purificationsystem, as recited in claim 1, wherein said catalytic absorbent isammonia, which is adapted as both catalyst for increasing a reactionrate between said catalytic absorbent and said pollutants in saidflue-gas, and as reactant involving into said series reactions to formnon-toxic compounds of said final products therefrom.
 3. The flue-gaspurification system, as recited in claim 1, wherein said catalyticabsorbent is being delivered into said reactor in a multiple stagesmanner, wherein each of said stages in said reactor has a specificreactive conditions thereof for mainly reacting a targeted pollutant insaid flue-gas while further reacting with other said non-mainly-targetedpollutants.
 4. The flue-gas purification system, as recited in claim 1,further comprising a heat exchanger unit which is provided for gasifyingsaid catalytic absorbent, wherein said heat exchanger unit has at leasttwo sets of pipes, wherein said flue-gas is flowing within a first setof said pipes as a heat transfer medium while said catalytic absorbentis flowing within a second set of said pipes for heat exchanging withsaid flue-gas, so as to be gasified before entering said reactor.
 5. Theflue-gas purification system, as recited in claim 1, further comprisinga dust remover which is provided to communicatively connect with saidreactor for removing dust in said flue-gas and solid compounds of saidfinal products.
 6. The flue-gas purification system, as recited in claim5, wherein said dust remover comprises a dust removing device forremoving said dust and said solid compounds of said final products and asolid product collector for further separating ammonium salts of saidsolid compounds of said final products, so as for reclamation of saidfinal products from said flue-gas.
 7. The flue-gas purification system,as recited in claim 1, further comprises a fog separator for separatingsaid catalytic absorbent from purified flue-gas after said purifiedflue-gas exit said reactor.
 8. The flue-gas purification system, asrecited in claim 1, further comprising a monitoring system formonitoring and collecting a plurality of parameters of said purificationsystem, wherein said monitoring system is further electrically linkingwith said absorbent adding system for automatically adding andcontrolling a flow rate of said catalytic absorbent entering into saidreactor.
 9. The flue-gas purification system, as recited in claim 4,wherein said flue-gas has a temperature around 120° C. to 160° C. beforeentering into said heat exchanger unit a temperature around 60° C. to80° C. before entering into said reactor, and a temperature around 25°C. to 50° C. when exiting said purification system and being dischargedinto the air.
 10. The flue-gas purification system, as recited in claim1, wherein said pollutants of said flue-gas is selected from a groupconsisting of SOx, NOx, CO2, HF, HCl, HNO3, H2S, H2SO4, which beingremoved via a series of denitrification processes.
 11. The flue-gaspurification system, as recited in claim 1, wherein said pollutants ofsaid flue-gas comprises nitrogen oxides being removed via a series ofdenitrification processes having chemical equations of said seriesreactions in said reactor below:2NO+O₂→2NO₂2NO₂+NH₃—H₂O→NH₄NO₃+HNO₂HNO₂+NH₃→NH₄NO₂.
 12. The flue-gas purification system, as recited inclaim 1, wherein said pollutants of said pollutants of said flue-gascomprises sulfur oxides, which is being removed through a series ofmulti-chemical processes comprising acid-base reactions, oxidationreactions, and chain reactions, wherein said acid-base reactions havethe chemical equation below:NH₃—H₂Og _((Gas))+SO₂ g _((Gas))→NH₄HSO_(3s)2NH₃—H₂Og _((Gas))+SO₂ g _((Gas))→(NH₄)₂SO₃ wherein said oxidationreactions have the chemical equation below:NH₄HSO_(3s)+O_(2g)→NH₄HSO_(4s)NH₄HSO_(4s)+NH₃→(NH₄)₂SO₄NH₄HSO_(3s)+NO_(2g)→NH₄HSO_(4s)+NONH₄NO₃+NH₄HSO₃→(NH₄)₂SO₄+HNO_(2g) wherein said chain reactions have thechemical equations below:HONOg+hν---→OH+NOOH+SO₂--→H₂SO₄NH₃+H₂SO₄--→NH₄HSO₄NH₃+NH₄HSO₄--→(NH₄)₂SO₄.
 13. The flue-gas purification system, asrecited in claim 1, wherein said pollutants of said flue-gas comprisescarbon dioxide, which is being removed via decarbonization process insaid reactor having the chemical equation below:CO₂+NH₃—H₂O→NH₄HCO₃NH₄HCO₃+NH₃→(NH₄)₂CO₃.
 14. The flue-gas purification system, as recitedin claim 1, wherein said reactor is a Venturi type reactor.
 15. Theflue-gas purification system, as recited in claim 1, wherein saidcatalytic absorbent is a mixture of gasified ammonia and an oxygencontained matter, wherein a volume proportion of said gasified ammoniaand said oxygen contained matter is 0 to
 100. 16. The flue-gaspurification system, as recited in claim 15, wherein said oxygencontained matter is selected from a group consisting of oxygen, air,oxidized air, gasified hydrogen peroxide, and ozone.
 17. The flue-gaspurification system, as recited in claim 1, wherein said reactingtemperature is preferred at −30° C. to 140° C.
 18. A method of purifyingflue-gas, comprising the steps of: (A) conveying a flue-gas into areactor; (B) gasifying a catalytic absorbent into a gas phase thereofand conveying said gasified catalytic absorbent into said reactor forreacting with two or more pollutants of said flue-gas therein to form aseries of reactions therebetween under a homogenous gas-gas phasecondition and a reacting temperature at 160° C. or less to form finalproducts in solid state to efficiently purify said flue-gas; and (C)discharging said purified flue-gas into air.
 19. The method, as recitedin claim 18, wherein said catalytic absorbent is ammonia, which isadapted as both catalyst for increasing a reaction rate between saidcatalytic absorbent and said pollutants in said flue-gas, and asreactant involving into said series reactions to form non-toxiccompounds of said final products therefrom.
 20. The method, as recitedin claim 18, wherein in the step (B), said catalytic absorbent is beingdelivered into said reactor in a multiple stages manner, wherein each ofsaid stages in said reactor has a specific reactive conditions thereoffor mainly reacting a targeted pollutant in said flue-gas while furtherreacting with other said non-mainly-targeted pollutants.
 21. The method,as recited in claim 18, further comprising a step of providing a heatexchanger unit for gasifying said catalytic absorbent, a step ofdelivering said flue-gas into a first set of pipes of a heat exchangerof said heat exchanger unit as heat transferring medium, and a step ofdelivering said catalytic absorbent into a second set of pipes of saidheat exchanger for exchanging heat from said flue-gas, so as to begasified before entering said reactor.
 22. The method, as recited inclaim 18, before the step (c), further comprising a step of removingdust in said reactor, wherein said dust includes fly ash in saidflue-gas and yield solid phase of said final product from said seriesreactions in said reactor.
 23. The method, as recited in claim 22,further comprising a step of collecting solid ammonium salt of saidyield solid phase of said final product so as to further utilize saidfinal product for reclamation of said flue-gas.
 24. The method, asrecited in claim 18, after said flue-gas is reacted with said catalyticabsorbent for purifying said flue-gas, further comprising a step ofseparating said catalytic absorbent and said purified flue-gas so as tofurther purify said flue-gas and reuse said catalytic absorbent of saidcatalytic absorbent.
 25. The method, as recited in claim 18, furthercomprising detecting variety of reactive conditions and parameters atany measuring point of said purification system while electricallylinking with said absorbent adding system for controllably.
 26. Themethod, as recited in claim 18, wherein said reactor is a Venturi typereactor.
 27. The method, as recited in claim 21, wherein said flue-gashas a temperature around 120° C. to 160° C. before entering into saidheat exchanger unit a temperature around 60° C. to 80° C. beforeentering into said reactor, and a temperature around 25° C. to 50° C.when exiting said purification system and being discharged into the air.28. The method, as recited in claim 18, wherein said pollutants of saidflue-gas is selected from a group consisting of SOx, NOx, CO2, HF, HCl,HNO3, H2S, H2SO4, which being removed via a series of denitrificationprocesses.
 29. The method, as recited in claim 18, wherein saidpollutants of said flue-gas comprises nitrogen oxides, which is beingremoved via a series of denitrification processes of said seriesreactions having the chemical equations thereof in said reactor below:2NO+O₂→2NO₂2NO₂+NH₃—H₂O→NH₄NO₃+HNO₂HNO₂+NH₃→NH₄NO₂.
 30. The method, as recited in claim 18, wherein saidpollutants of said pollutants of said flue-gas comprises sulfur oxides,which is being removed through a series of multi-chemical processes ofsaid series reactions comprising acid-base reactions, oxidationreactions, and chain reactions, wherein said acid-base reactions havethe chemical equation below:NH₃—H₂Og _((Gas))+SO₂ g _((Gas))→NH₄HSO_(3s)2NH₃—H₂Og _((Gas))+SO₂ g _((Gas))→(NH₄)₂SO₃ wherein said oxidationreactions have the chemical equation below:NH₄HSO_(3s)+O_(2g)→NH₄HSO_(4s)NH₄HSO_(4s)+NH₃→(NH₄)₂SO₄NH₄HSO_(3s)+NO_(2g)→NH₄HSO_(4s)+NONH₄NO₃+NH₄HSO₃→(NH₄)₂SO₄+HNO_(2g) wherein said chain reactions have thechemical equations below:HONOg+hν---→OH+NOOH+SO₂--→H₂SO₄NH₃+H₂SO₄--→NH₄HSO₄NH₃+NH₄HSO₄--→(NH₄)₂SO₄.
 31. The method, as recited in claim 18, whereinsaid pollutants of said flue-gas comprises carbon dioxide, which isbeing removed via decarbonization process in said reactor having thechemical equation below:CO₂+NH₃—H₂O→>NH₄HCO₃NH₄HCO₃+NH₃→(NH₄)₂CO₃.
 32. The method, as recited in claim 18, whereinsaid catalytic absorbent is a mixture of gasified ammonia and an oxygencontained matter, wherein a volume proportion of said gasified ammoniaand said oxygen contained matter is 0 to
 100. 33. The method, as recitedin claim 32, wherein said oxygen contained matter is selected from agroup consisting of oxygen, air, oxidized air, gasified hydrogenperoxide, and ozone.
 34. The method, as recited in claim 18, whereinsaid reacting temperature is preferred at −30° C. to 140° C.